1. Field of the Invention
The present invention relates to a double row tapered roller bearing unit and particularly relates to a double row tapered roller bearing unit applied to a rotation support for rotatably supporting a shaft portion (rotation axis) of a printer cylinder, a rolling mill roller, or other rotating member of any of various industrial machines on a frame or other fixed portion.
2. Related Art
In an offset printer, a plate cylinder, a blanket cylinder, and an impression cylinder are disposed in parallel, and in a printing process, the blanket cylinder contacts outer circumferential surfaces of the plate cylinder and the impression cylinder and transfers and prints printing image, transferred from the plate cylinder, onto a printing sheet passing between the blanket cylinder and the impression cylinder. When a sheet jam occurs due to printing troubles, etc., the three cylinders must be positioned apart from each other, and a jammed sheet is removed upon moving an axial center of the blanket cylinder away from respective axial centers of the plate cylinder and the impression cylinder so that ink on the blanket cylinder does not become transferred onto the printing sheet.
A double row tapered roller bearing unit, having a double structure such as shown in FIGS. 11 and 12, is known as a device for rotatably supporting such a blanket cylinder (see, for example, Patent Document 1). Each of the double row tapered roller bearing units 100 and 100′ shown in FIGS. 11 and 12 is constituted of an outer bearing 101 and an inner bearing 102, and an intermediate ring 105, which constitutes inner ring raceway surfaces 103 of the outer bearing 101 and outer ring raceway surfaces 104 of the inner bearing 102, is formed eccentric to the axial center of the blanket cylinder, thereby allowing the above-described operation and high-speed rotation of the blanket cylinder. The outer bearing 101 and the inner bearing 102 are respectively configured in back-to-back combinations to improve bearing stiffness.
In the double row tapered roller bearing unit 100 shown in FIG. 11, the intermediate ring 105 is split in two at a central position in an axial direction into a pair of split rings 105a, 105a. In the double row tapered roller bearing unit 100′ shown in FIG. 12, while the intermediate ring 105 has an integrated structure, a cage 108, incorporating an outer ring 106 and tapered rollers 107, is split in two in a circumferential direction to facilitate assembly of the outer bearings 101 as shown in FIG. 13.    Patent Document 1: Japanese Published Unexamined Patent Application JP-A-2004-108572